I went into one of these stores to shop and when I was paying for my stuff I asked the manager: "so what does OMG stand for?" and he said "what do you say when you see all these amazing prices?" :) So corny

These stores have been around NY since the mid-1980s (long before OMG was used in IM, etc). It's a great store and I've been getting great deals there for years. The funny thing is that they've always told people that it stands for Oh My God (or Goodness, depending on who you ask).